The most unusual thing about writer/director Jeremy Toback's "Black and White" is that he actually thought it would be a GOOD idea to allow Mike Tyson to improvise.

Mike Tyson is not an actor, of course; he's a boxer/rapist who speaks in a squeaky, barely comprehensible patter even when he knows what he's going to say. Yet even he, playing himself, doesn't come up with the worst performance in the movie. In a film marked by bad performances even from good actors (as well as some by known bad actors), it's a toss-up who's worst. Is it Robert Downey Jr. as the gay husband of an amateur documentary filmmaker played by Brooke Shields, or is it bland-and-laughable Shields herself? Which of the two mumbly monotoned catatonic hip-hoppers is worse? The basketball player trying to act, or the musician trying to act?

About 30 minutes into the film, I jotted down, "What is this movie about?!" It's over now and I still don't really know, so explaining it will be difficult. Shields's character, a nose-ringed NYU graduate, is doing a documentary about the phenomenon of white high school kids who dress, talk and act black, having been influenced by the hip-hop culture. There's a group of those kids whom we sort of follow and sort of get to know, as well as the people who actually are black with whom some of them are connected, primarily by way of sex. A number of subplots jostle for screen time, but the central one seems to be a college basketball player named Dean (Allan Houston) who is bribed by Mark Clear (Ben Stiller) to throw a game, which leads to dire consequences and third-act plot twists. His friend Rich (Oliver "Power" Grant), a big-shot Harlem gangster, gets dragged into it, and things are downhill from there.

As much as anything, "Black and White" is about sex: interracial sex, homosexual sex, sex for revenge, sex for rebellion, etc., etc. It's also about the hip-hop culture. What the film fails to do, however, is actually SAY anything about either subject. There's plenty of sex and plenty of hip hop, but so what? Showing us a lot of examples of your subjects is not the same as giving insight into them.

Much of the film was improvised -- a risky move in any case, but especially when dealing with such a large number of non-actors. Much of the dialogue is stilted and forced, and not one of the characters ever comes across as compelling. Some of them may be realistic insofar as there really are a lot of people who say the F-word 12 times per sentence, but the guy sitting next to me at the bus stop might be realistic, too, and that doesn't mean I'd want to watch a movie about him.

The soundtrack is stellar, and Ben Stiller outclasses everyone in the film with a performance that actually borders on funny (far below his usual status, but better than everyone else here). But Tyson and Downey have a scene that is one of the most uncomfortable, embarrassing pieces of work I've seen in a while, and I have seen a LOT of community theater. Still, at least their scene was interesting to watch, like a train wreck. The rest of the movie, a hodge-podge of unclear themes and pointless scenes, hardly even warrants that much attention.